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Unravelling
the mysteries of stellar winds with polarimetric
observations of
millisecond pulsars
Xiaopeng
YOU
Outline•
Pulsar wind from J1748-2446A
•
Solar wind effect by J1730-2304
Basic properties of J1748-2446A•
Discovered in 1990, Parkes
telescope, 20-cm
(Lyne
et al., 1990)•
Locating in the globular cluster Terzan
5
•
Period : 11.56 ms•
Dispersion Measure: 242.0
•
Circular orbital period: 1.8 hours•
Projected semi-major axis: 0.119 light second
•
Companion: White drawf, 0.089 Mʘ•
Eclipsing time: variable, depending on frequency, greater than Roche lobe, 0.2 Rʘ
•
Sometimes disappearing
•
3 observations at 20cm•
2 observations at 10/50 cm.
•
Almost all observations cover whole orbital phase.
Observations
Eclipsing : 20 cm
Eclipsing : 50 cm
Eclipsing : 10 cm
Depolarization Phenomenon•
3-min sub-integration
•
Searching for RM and showing polarization profiles.
•
RM: 173.6 rad
m-2
•
found PSR-WD system with depolarization phenomenon
Polarization profiles•
10 cm: no linear polarization, because of weak signal and low linear polarization
Polarization properties VS orbital phase
Turbulence of Pulsar wind
2 4RM 1s l >
2 2 40 RM( ) exp( 2 )P Pl s l= -
Orbital Phase [0.7,0.8] < 4
[0.55, 0.7] [0.8,0.9]others
•
Depolarization due to turbulence of Faraday Rotation (Burn 1996)
•
Lower frequency, easier depolarized
•
Assume significant depolarization when
2RM (rad m )s -
RM4 25s< <
RM25 100s< <
Conclusions •
Obtain polarization profiles for 3 bands for the eclipsing pulsar PSR J1748-2446A
•
Found no eclipse at 10 cm•
Found PSR-WD system with depolarization phenomenon
•
Duration of both total eclipse and depolarization depend on frequency
•
Depolarization because of turbulence of Faraday rotation of pulsar wind
•
Help understanding the eclipse mechanism
Some research of solar wind by J1730-2304
•
Using a millisecond pulsars PSR J1730- 2304 (be
=0.19o) •
Obtain both RM and DM from the solar wind
•
Model fitting our measurement to obtain magnetic field of solar wind (more work to do)
Obtain RM from the Sun•
Adjust RM to optimize the linearly polarized intensity, depolarization
•
Separate the each observation into two halves •
Calculating PA difference close and far from the Sun
•
Subtracting the contribution from ionosphere (IRI model)
141216:22:33 R0=6.4 Rs
PA=135.4o, RMs=49.2 rad
m-2
Obtain DM from the Sun•
Fitting timing model
•
Obtain extra timing residual from the Sun
Obtain DM from the Sun•
Fitting timing model
•
Obtain extra timing residual from the Sun
141216:22:33
R0=6.4 Rs
t=15.4μs, DMs=7.0X10-3
cm-3pc
Observational results
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